Truck not heating up

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[ARCHIVED THREAD] - Truck not heating up

Posted: 1/1/2006 4:55:53 PM EDT

My 92 Blazer (fullsize 5.7L) isn't heating up according to the gauge. It usually runs at 190-200 degrees, but lately its only been heating up to 140 or so. I changed the thermostat and it still only gets up to 140. The heat works fine.

I talked to a mechanic and he said as long as the heat and eveything is working fine not to worry about it. Its possible the gauge is wrong, as my oil pressure gauge hasn't worked in 5 or 6 years, but any other ideas?

Posted: 1/1/2006 6:55:32 PM EDT

[#1]

Just taking a stab in the dark here but..do you have a clutch type fan? If so..is it still working or is the clutch part seized up making the fan turn all the time?

Posted: 1/1/2006 8:25:28 PM EDT

[#2]

Quoted:
Just taking a stab in the dark here but..do you have a clutch type fan? If so..is it still working or is the clutch part seized up making the fan turn all the time?

I'm not sure. How do I know if I have a clutch type fan? I'll check tomorrow to see if the fan is on when I first start it up.

Posted: 1/1/2006 8:31:49 PM EDT

[#3]

Check to see if your radiator cap is any good. I had a Ford 5.0 that had a bad cap and it would freeze me out in the winter until I replaced the cap. It wouldn't seal and allow pressure to build in the cooling system that it needs to work properly.

Posted: 1/1/2006 9:13:38 PM EDT

[#4]

Quoted:
Quoted:
Just taking a stab in the dark here but..do you have a clutch type fan? If so..is it still working or is the clutch part seized up making the fan turn all the time?

I'm not sure. How do I know if I have a clutch type fan? I'll check tomorrow to see if the fan is on when I first start it up.

A clutch type fan would have a big ol' aluminum housing behind the fan blades, an electric fan would have an electric motor

Posted: 1/2/2006 3:52:36 AM EDT

[#5]

Quoted:
Quoted:
Quoted:
Just taking a stab in the dark here but..do you have a clutch type fan? If so..is it still working or is the clutch part seized up making the fan turn all the time?

I'm not sure. How do I know if I have a clutch type fan? I'll check tomorrow to see if the fan is on when I first start it up.

A clutch type fan would have a big ol' aluminum housing behind the fan blades, an electric fan would have an electric motor

If you have a clutch type fan that is working..you should be able to turn it by hand with the engine off. Unless the clutch is seized..

This is what it looks like..from the front.

Yous won't have as many blades on it though.

Posted: 1/2/2006 4:10:45 AM EDT

[#6]

Most people will complain about a ROARING noise if a clutch
fan is locked up . They get pretty loud at 3K RPM's .

It also wont effect operating engine temp with
a working thermostat . The stat would close off
flow below it's operating temp to keep the engine hot .
That's why it's there .

Since you say the heat is fine . It's more then likely
that your gauge or sender is faulty . If coolent temp
was actually 140° then you would only be getting
around 100° out the vents . Where normal is 150-160°

Posted: 1/2/2006 5:00:56 AM EDT

[#7]

brings up a good point, if the temp gauge is faulty, is there anyway to measure coolant temp with say an old fashioned thermometer without getting scalded? Everything's under pressure so you cant just pop the radiator cap and stick a probe in there.

I never diagnosed temp gauges, I'm guessing if the temp sensor is electronic you can test it's voltage output with a volt meter and at least determine if the sensor is working or not

Posted: 1/2/2006 7:41:12 AM EDT

[#8]

Probably a bad sender.

Posted: 1/2/2006 6:48:21 PM EDT

[#9]

Quoted:
Most people will complain about a ROARING noise if a clutch
fan is locked up . They get pretty loud at 3K RPM's .

It also wont effect operating engine temp with
a working thermostat . The stat would close off
flow below it's operating temp to keep the engine hot .
That's why it's there .

Since you say the heat is fine . It's more then likely
that your gauge or sender is faulty . If coolent temp
was actually 140° then you would only be getting
around 100° out the vents . Where normal is 150-160°

That's why I put the stab in the dark disclaimer in..

[ARCHIVED THREAD] - Truck not heating up

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